Just three months since the last show from Lost in the Trees, the orchestral indie rock act he led for seven years, he is but a week away from the two-night world premiere of Lion and the Lamb, a new concert-length performance that uses his academic background in composition to plunder the poems of Rainer Maria Rilke. But he's not exactly excited about putting the final pieces in place. After a half-decade of tour vans, the expectations of the classical world are daunting.

"I really want this to be over with," Picker says, laughing. "The indie world and the performing arts world are on such different schedules. The performing arts world is thinking a year and a half or a season ahead, while the indie rock world is thinking a few months ahead. Trying to get those two worlds to commit [to each other] is logistically difficult."

Still, Lion and the Lamb is both a fitting extension of Picker's time with Lost in the Trees and a confident step away from the confines of an indie rock act. He's even assembled an ensemble that reflects both worlds, with a string quartet on loan from New Music Raleigh paired with area musicians from bands such as Bowerbirds, The Hot at Nights, Hiss Golden Messenger and Big Star's Third. Picker will not sing, but he will reluctantly play bass—a reduced role that reflects his desire to get out of the rock band spotlight and deep into the privacy composition can offer.

Lion and the Lamb began to take shape as Picker finished Past Life, the final Lost in the Trees album. Lost in the Trees had always been a large band, with a string and horn entourage that sometimes pushed membership beyond a dozen. While Past Life held on to some orchestral elements, it offered a clear stylistic departure, with more electric guitars and synthesizers pushed to the forefront. Picker listened to lots of pop and electronic music while writing and recording the material.

But by the time the record was finished, he was sick of that music and his own songwriting. He turned to minimalist or modern composers—Philip Glass, Arvo Pärt, Gavin Bryars. They led him to refocus on composition, or music made outside of what he calls "the band world."

"The day that I got back from the studio from making Past Life," Picker remembers, "I started jotting this thing down."

With Lost in the Trees, Picker balanced mournful lyrics, often about his mother's tragic life and death, with rich arrangements. He confined those ideas to single-song lengths, even when those tunes worked together as a concept album, as with 2012's A Church That Fits Our Needs. But Lion and the Lamb is neither an album nor a song; it is a long, flowing, unified piece.

Picker began building the music during soundchecks for what became Lost in the Trees' final tours. Some elements even date back to his time at the Berklee College of Music, where he would score obscure French-Canadian films. Half of the finished work is entirely instrumental, incorporating elements of jazz and improvisation. It's new terrain for Picker.

"I'm assuming people will think it's weird, but I don't know," he says. "There are really bizarre time signatures and stabbing elements, but on top of that there's a beautiful melody or vice versa."

Several years ago, the director of a play Picker was scoring pointed him in Rilke's direction. He used one poem as the basis for a piece of the score and kept studying the German master. Rilke's collection The Book of Hours—plus his epitaph and two other poems—emerged as a fitting lyrical foundation for Lion and the Lamb.

"My music and the environment I'd been trying to create for my own voice really naturally fit with the Rilke poetry," he says. "It was that fluidity or naturalness that got me really excited about doing the project."

In Rilke's poetry, Picker saw a chance to use words that resonated with him but didn't draw on his personal narrative. After years of confessing his own story in Lost in the Trees, he could get outside of his head. Rilke's poems were often published as "love poems to God," because they directly address contradictory struggles with spirituality. The pieces that most resonated with Picker approach light and dark with equal measure. And though The Book of Hours was first published in 1905, Picker found that Rilke's reflections on human distraction and desensitization applied even more to an era enraptured with its technological toys.

"For me, writing songs always feels like going to church a little bit," he says. "It allows me to exist with some unexplainable things. Working with this poetry was an opportunity to exist with a lot of feelings without having to explain things or be too academic."

This idea of existing without explaining bleeds into the presentation of Lion and the Lamb, too. Though Picker will help perform the premiere, he had hoped to sit it out and simply watch his work be delivered by others. But strict schedules wouldn't allow it. He wants to publish Lion and the Lamb as a work other groups can play, so perhaps he can relax and listen in the future.

Such distaste for the spotlight was a primary impetus for ending Lost in the Trees. On the road, on a new stage every night, that attention was impossible to avoid.

"I don't know where I sit anymore, but all I know is I can't tour anymore. I've lost my mind," Picker jokes. His goals are now a little loose. "Maybe I'll be a carpenter."

But the privacy and distance of composition seem to be a sustainable alternative for Picker. That is, so long as he survives the vast crossover logistics of his first premiere.